Frequencies of Terrestrial Television Channels

DTVStudent

Hi Folks,

I am trying to summarize what I have learned about broadcast frequencies and how to calculate the wavelength of a given frequency in meters and inches. As I understand it, the wavelength is important for building a do it yourself antenna. Please check the accuracy of the following text.


All television stations in the United States of America broadcasting terrestrial signals are licensed by the Federal Communications Commission. The FCC assigns the maximum power and center frequency of each channel. Every channel is limited to a 6 MHz bandwidth, or ±3 MHz about its center frequency.

The older VHF television channels, 2 through 13, were broken up into three contiguous bands. Channels 2 through 4 operated between 54 MHz and 72 MHz. Channels 5 through 6 operated between 76 MHz and 88 MHz. Channels 7 through 13 operated between 174 MHz and 216 MHz. Channels 2 through 6 are often referred to as the VHF-LO band and channels 7 through 13 as the VHF-HI band.

Sometime later, the FCC allocated frequencies 470 MHz through 884 MHz in the UHF band, to channels 14 through 82. The frequencies used by channels 70 through 82 were reassigned as the demand for cell phone communication grew. Early in 2009, the FCC will also reallocate the frequencies used by channels 52 through 69.

The center frequency of each channel can be calculated as following:

Channels 2 through 4: Frequency in MHz = (6 X Channel Number) + 45

Channels 5 through 6: Frequency in MHz = (6 X Channel Number) + 49

Channels 7 through 13: Frequency in MHz = (6 X Channel Number) + 135

Channels 14 and above: Frequency in MHz = (6 X Channel Number) + 389

Example: Calculate the Wavelength (λ) of Channel 32.

Center Frequency = (6 X 32) + 389 = 581 MHz
Frequency Band = (581 - 3) through (581 + 3) MHz = 578 through 584 MHz

Wavelength of 578 MHz = 300/578 meters = 0.519031 meters
Wavelength of 578 MHz = 300/578 meters X 39.37 in/meter = 20.4343 inches

Wavelength of 584 MHz = 300/584 meters = 0.513699 meters
Wavelength of 584 MHz = 300/584 meters X 39.37 in/meter = 20.2243 inches


I would appreciate your comments.

Thank you,
DTV Student

donnyjaguar

By first glance, I do believe you have it right.

What I find useful is a spreadsheet I made up which has all the TV channel frequencies. For each channel I also have the analogue FM carrier frequency and the DTV video carrier frequency. These are useful to punch into my scanning receiver to very accurately aim antennas for best signal. You can also programme in DX channels and scan. When the band opens up the scanner will start to make all sorts of noise.

rbinck

Double check here: FREQUENCY-LENGTH

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rrrrrroger

Yes that works, but the correct formula is:

wavelength (m) == speed of light (m/s) / frequency (1/s)
== (300,000,000 m/s) / (578,000,000 1/s)
== ______ meters



(where 1/s == inverse seconds == "cycles per second")

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